Neisseria gonorrhoeae is an evolving species of bacteria. The strains isolated recently from persons with gonorrhea exhibit great diversity of nutritional requirements and susceptibilities to antibacterial drugs. We are currently examining the enzymatic defects of the pathways for the biosynthesis of arginine and methionine and are making quantitative determination of the bacterial responses to 14 drugs. The mutant markers from patient isolates will be used in experiments to establish the linkage relationships to various genetic determinants by DNA-mediated transformation.